Duplicate font in PDF causes prepress RIP failure

Question

I've scanned various forums trying to get a handle on this problem but nothing seems to get at this issue.
A book that we've built with InDesign generates pdfs that show a duplicate MyriadPro-Light font embedded in the document. The second iteration of the font has a different icon and is listed with as Type 1(CID) with Encoding: Identity-H. The Acrobat Pro PDF/X-1a preflight doesn't flag any issues with the file, but when I sent the file to prepress their RIP flagged the MyriadPro-Light font as having inadequate permissions. They were unable to substitute a font or bypass the error. What's more, they were unable to print from the packaged source files I provided - getting the same error. They had to brute-force open individual pdf pages in Illustrator, convert to outlines, generate an eps and place 170 eps pages in Quark to get a file that would RIP.
Here's an image link that shows the two MyriadPro-Light font entries with the balky one highlighted.
http://home.comcast.net/~bjnicholls/fileaccess/EmbeddedFontsAcrobatPro.jpg
I've looked for duplicate MyriadPro installations in my XP SP2 system fonts folder and in the common files/adobe/fonts folder. There were duplicates for several MyriadPro fonts, but only the Light variant is acting up. From what I've gleaned, the Indentity-H suggests the font is a screen font or something along those lines.
I moved all the OTF fonts from the common files Adobe fonts folder trying to troubleshoot the problem. I bypassed my FontAgent Pro utility and ensured the MyriadPro OTF fonts were installed in the system fonts folder with no fonts with similar names.
I theorized that pdf and eps graphics placed in the book documents may have a font variant embedded in them, so I went through all the placed vector format files and converted type to outlines. A subsequent pdf export shows the same duplicate font problem.
I'd appreciate help with a strategy to track down the offending font. There are 11 documents assembled into one InDesign book, I'm generating a book pdf from the book dialog window. I've opened each document looking for font error messages and found none. In each document, Myriad Pro Light shows normally in the font pulldown lists and behaves normally.
Some of the document files were worked on via a Mac. As far as I know the same Adobe Opentype fonts were used by that designer. The documents started out in InDesign CS2, but as my collaborator acquired CS3 we've moved the document into the new version.
In addition to diagnostic strategy advice, I'd appreciate information or links to explain Adobe's application font strategy (dedicated font folders in both the common program files folder and so-called "private" font folders associated in the application folder tree). I've seen many threads where this fragmentation of installed fonts causes confusion and I'd like to understand what Adobe's intent is with this separate font management system.
I suppose I should ask this in the Acrobat forum, but I don't understand why this font issue isn't flagged in Acrobat preflight checking.
Thanks for any light you can shed on these questions.

Answer 1

Therer is absolutely nothing wrong with the scenario of a PDF file having one font subset as regular Type 1 and another as a double byte CID encoded. That is all perfectly kosher per the PDF specification. As such, no PDF/X preflight or any other rational preflight profile will flag this as an error since it is not an error!
I suspect that the "problem" is not that there are two subsets of a particular font, one as a regular Type 1 font and the other as a CID-encoded font, but rather, that there is a problem with the RIP itself not being able to properly deal with CID-encoded fonts. The fact is that CID-encoding has been part of the PostScript language specification for well over 10 years (standard in PostScript 3 and most PostScript Level 2 printers can handle these fonts - even my 12 year old LaserJet 5M can handle them!) and the general PDF specification since Acrobat 4 / PDF 1.3 in 1999 (although Acrobat 3 did support them for CJK Asian fonts).
Note that the scenario you offer occurs not only with InDesign, but with Illustrator, Photoshop, and Acrobat Distiller. All of them can yield PDF files that would be a problem for your printer's RIP.
Looks like your printer needs to update their software to some reasonable level.
- Dov